This invention relates to medical X-ray tables and more specifically to tilt drives and safety restraint apparatus therefor.
For general X-ray diagnostic use as well as for many specialized uses it is very desirable if not necessary to move a patient resting upon an X-ray table into different orientations. One of the more common and useful movements is a tilting movement, where the patient is brought from standing position to prone position or vice versa. A convenient height for the table results in a rotation axis that is not at the center of the table, which causes a weight unbalance. The weight unbalance tends to make the table abruptly fall to a rest position in the event of mechanical failure of the tilt drive therefor. An abrupt fall of the table can easily injure an attendant or the patient supported on the table.
One solution is to better balance the table either by effectively moving the rotation axis closer to center or by using a counterweight for the table. A more practical solution is to prevent the table from falling abruptly with some kind of safety apparatus. Shock absorbers have been used for this purpose. Shock absorbers do not prevent a falling of the table, but rather safely limit the rate of fall. Another approach has been to design the table tilt drive so that mechanical failure will not occur due to the high mechanical reliability of the tilt drive. Heavy gear trains and rack and pinion arrangements have been used for this purpose.
It is an object of the present invention to prevent an abrupt fall of the X-ray table in the event of mechanical failure of the table tilt drive.
A further object is to prevent any substantial falling of the X-ray table at all in the event of mechanical failure of the table tilt drive.
Another object is to provide a safety restraint apparatus which safely allows use of tilt drive constructions which are susceptible to possible mechanical failure.
Still another object is to provide a less expensive tilt drive which is nevertheless safe to use.
A further object is to provide safety apparatus for a table tilt drive which allows continued temporary use of the table even after mechanical coupling failure in the tilt drive.